include/linux/backing-dev.h

   1 /*
   2  * include/linux/backing-dev.h
   3  *
   4  * low-level device information and state which is propagated up through
   5  * to high-level code.
   6  */
   7
   8 #ifndef _LINUX_BACKING_DEV_H
   9 #define _LINUX_BACKING_DEV_H
  10
  11 #include <linux/percpu_counter.h>
  12 #include <linux/log2.h>
  13 #include <linux/proportions.h>
  14 #include <linux/kernel.h>
  15 #include <linux/fs.h>
  16 #include <linux/sched.h>
  17 #include <linux/timer.h>
  18 #include <linux/writeback.h>
  19 #include <linux/atomic.h>
  20
  21 struct page;
  22 struct device;
  23 struct dentry;
  24
  25 /*
  26  * Bits in backing_dev_info.state
  27  */
  28 enum bdi_state {
  29         BDI_pending,            /* On its way to being activated */
  30         BDI_wb_alloc,           /* Default embedded wb allocated */
  31         BDI_async_congested,    /* The async (write) queue is getting full */
  32         BDI_sync_congested,     /* The sync queue is getting full */
  33         BDI_registered,         /* bdi_register() was done */
  34         BDI_writeback_running,  /* Writeback is in progress */
  35         BDI_unused,             /* Available bits start here */
  36 };
  37
  38 typedef int (congested_fn)(void *, int);
  39
  40 enum bdi_stat_item {
  41         BDI_RECLAIMABLE,
  42         BDI_WRITEBACK,
  43         BDI_WRITTEN,
  44         NR_BDI_STAT_ITEMS
  45 };
  46
  47 #define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
  48
  49 struct bdi_writeback {
  50         struct backing_dev_info *bdi;   /* our parent bdi */
  51         unsigned int nr;
  52
  53         unsigned long last_old_flush;   /* last old data flush */
  54         unsigned long last_active;      /* last time bdi thread was active */
  55
  56         struct task_struct *task;       /* writeback thread */
  57         struct timer_list wakeup_timer; /* used for delayed bdi thread wakeup */
  58         struct list_head b_dirty;       /* dirty inodes */
  59         struct list_head b_io;          /* parked for writeback */
  60         struct list_head b_more_io;     /* parked for more writeback */
  61         spinlock_t list_lock;           /* protects the b_* lists */
  62 };
  63
  64 struct backing_dev_info {
  65         struct list_head bdi_list;
  66         unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */
  67         unsigned long state;    /* Always use atomic bitops on this */
  68         unsigned int capabilities; /* Device capabilities */
  69         congested_fn *congested_fn; /* Function pointer if device is md/dm */
  70         void *congested_data;   /* Pointer to aux data for congested func */
  71
  72         char *name;
  73
  74         struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS];
  75
  76         unsigned long bw_time_stamp;    /* last time write bw is updated */
  77         unsigned long written_stamp;    /* pages written at bw_time_stamp */
  78         unsigned long write_bandwidth;  /* the estimated write bandwidth */
  79         unsigned long avg_write_bandwidth; /* further smoothed write bw */
  80
  81         struct prop_local_percpu completions;
  82         int dirty_exceeded;
  83
  84         unsigned int min_ratio;
  85         unsigned int max_ratio, max_prop_frac;
  86
  87         struct bdi_writeback wb;  /* default writeback info for this bdi */
  88         spinlock_t wb_lock;       /* protects work_list */
  89
  90         struct list_head work_list;
  91
  92         struct device *dev;
  93
  94         struct timer_list laptop_mode_wb_timer;
  95
  96 #ifdef CONFIG_DEBUG_FS
  97         struct dentry *debug_dir;
  98         struct dentry *debug_stats;
  99 #endif
 100 };
 101
 102 int bdi_init(struct backing_dev_info *bdi);
 103 void bdi_destroy(struct backing_dev_info *bdi);
 104
 105 int bdi_register(struct backing_dev_info *bdi, struct device *parent,
 106                 const char *fmt, ...);
 107 int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev);
 108 void bdi_unregister(struct backing_dev_info *bdi);
 109 int bdi_setup_and_register(struct backing_dev_info *, char *, unsigned int);
 110 void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages);
 111 void bdi_start_background_writeback(struct backing_dev_info *bdi);
 112 int bdi_writeback_thread(void *data);
 113 int bdi_has_dirty_io(struct backing_dev_info *bdi);
 114 void bdi_arm_supers_timer(void);
 115 void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi);
 116 void bdi_lock_two(struct bdi_writeback *wb1, struct bdi_writeback *wb2);
 117
 118 extern spinlock_t bdi_lock;
 119 extern struct list_head bdi_list;
 120 extern struct list_head bdi_pending_list;
 121
 122 static inline int wb_has_dirty_io(struct bdi_writeback *wb)
 123 {
 124         return !list_empty(&wb->b_dirty) ||
 125                !list_empty(&wb->b_io) ||
 126                !list_empty(&wb->b_more_io);
 127 }
 128
 129 static inline void __add_bdi_stat(struct backing_dev_info *bdi,
 130                 enum bdi_stat_item item, s64 amount)
 131 {
 132         __percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH);
 133 }
 134
 135 static inline void __inc_bdi_stat(struct backing_dev_info *bdi,
 136                 enum bdi_stat_item item)
 137 {
 138         __add_bdi_stat(bdi, item, 1);
 139 }
 140
 141 static inline void inc_bdi_stat(struct backing_dev_info *bdi,
 142                 enum bdi_stat_item item)
 143 {
 144         unsigned long flags;
 145
 146         local_irq_save(flags);
 147         __inc_bdi_stat(bdi, item);
 148         local_irq_restore(flags);
 149 }
 150
 151 static inline void __dec_bdi_stat(struct backing_dev_info *bdi,
 152                 enum bdi_stat_item item)
 153 {
 154         __add_bdi_stat(bdi, item, -1);
 155 }
 156
 157 static inline void dec_bdi_stat(struct backing_dev_info *bdi,
 158                 enum bdi_stat_item item)
 159 {
 160         unsigned long flags;
 161
 162         local_irq_save(flags);
 163         __dec_bdi_stat(bdi, item);
 164         local_irq_restore(flags);
 165 }
 166
 167 static inline s64 bdi_stat(struct backing_dev_info *bdi,
 168                 enum bdi_stat_item item)
 169 {
 170         return percpu_counter_read_positive(&bdi->bdi_stat[item]);
 171 }
 172
 173 static inline s64 __bdi_stat_sum(struct backing_dev_info *bdi,
 174                 enum bdi_stat_item item)
 175 {
 176         return percpu_counter_sum_positive(&bdi->bdi_stat[item]);
 177 }
 178
 179 static inline s64 bdi_stat_sum(struct backing_dev_info *bdi,
 180                 enum bdi_stat_item item)
 181 {
 182         s64 sum;
 183         unsigned long flags;
 184
 185         local_irq_save(flags);
 186         sum = __bdi_stat_sum(bdi, item);
 187         local_irq_restore(flags);
 188
 189         return sum;
 190 }
 191
 192 extern void bdi_writeout_inc(struct backing_dev_info *bdi);
 193
 194 /*
 195  * maximal error of a stat counter.
 196  */
 197 static inline unsigned long bdi_stat_error(struct backing_dev_info *bdi)
 198 {
 199 #ifdef CONFIG_SMP
 200         return nr_cpu_ids * BDI_STAT_BATCH;
 201 #else
 202         return 1;
 203 #endif
 204 }
 205
 206 int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio);
 207 int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
 208
 209 /*
 210  * Flags in backing_dev_info::capability
 211  *
 212  * The first three flags control whether dirty pages will contribute to the
 213  * VM's accounting and whether writepages() should be called for dirty pages
 214  * (something that would not, for example, be appropriate for ramfs)
 215  *
 216  * WARNING: these flags are closely related and should not normally be
 217  * used separately.  The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these
 218  * three flags into a single convenience macro.
 219  *
 220  * BDI_CAP_NO_ACCT_DIRTY:  Dirty pages shouldn't contribute to accounting
 221  * BDI_CAP_NO_WRITEBACK:   Don't write pages back
 222  * BDI_CAP_NO_ACCT_WB:     Don't automatically account writeback pages
 223  *
 224  * These flags let !MMU mmap() govern direct device mapping vs immediate
 225  * copying more easily for MAP_PRIVATE, especially for ROM filesystems.
 226  *
 227  * BDI_CAP_MAP_COPY:       Copy can be mapped (MAP_PRIVATE)
 228  * BDI_CAP_MAP_DIRECT:     Can be mapped directly (MAP_SHARED)
 229  * BDI_CAP_READ_MAP:       Can be mapped for reading
 230  * BDI_CAP_WRITE_MAP:      Can be mapped for writing
 231  * BDI_CAP_EXEC_MAP:       Can be mapped for execution
 232  *
 233  * BDI_CAP_SWAP_BACKED:    Count shmem/tmpfs objects as swap-backed.
 234  */
 235 #define BDI_CAP_NO_ACCT_DIRTY   0x00000001
 236 #define BDI_CAP_NO_WRITEBACK    0x00000002
 237 #define BDI_CAP_MAP_COPY        0x00000004
 238 #define BDI_CAP_MAP_DIRECT      0x00000008
 239 #define BDI_CAP_READ_MAP        0x00000010
 240 #define BDI_CAP_WRITE_MAP       0x00000020
 241 #define BDI_CAP_EXEC_MAP        0x00000040
 242 #define BDI_CAP_NO_ACCT_WB      0x00000080
 243 #define BDI_CAP_SWAP_BACKED     0x00000100
 244
 245 #define BDI_CAP_VMFLAGS \
 246         (BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP)
 247
 248 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \
 249         (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
 250
 251 #if defined(VM_MAYREAD) && \
 252         (BDI_CAP_READ_MAP != VM_MAYREAD || \
 253          BDI_CAP_WRITE_MAP != VM_MAYWRITE || \
 254          BDI_CAP_EXEC_MAP != VM_MAYEXEC)
 255 #error please change backing_dev_info::capabilities flags
 256 #endif
 257
 258 extern struct backing_dev_info default_backing_dev_info;
 259 extern struct backing_dev_info noop_backing_dev_info;
 260
 261 int writeback_in_progress(struct backing_dev_info *bdi);
 262
 263 static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits)
 264 {
 265         if (bdi->congested_fn)
 266                 return bdi->congested_fn(bdi->congested_data, bdi_bits);
 267         return (bdi->state & bdi_bits);
 268 }
 269
 270 static inline int bdi_read_congested(struct backing_dev_info *bdi)
 271 {
 272         return bdi_congested(bdi, 1 << BDI_sync_congested);
 273 }
 274
 275 static inline int bdi_write_congested(struct backing_dev_info *bdi)
 276 {
 277         return bdi_congested(bdi, 1 << BDI_async_congested);
 278 }
 279
 280 static inline int bdi_rw_congested(struct backing_dev_info *bdi)
 281 {
 282         return bdi_congested(bdi, (1 << BDI_sync_congested) |
 283                                   (1 << BDI_async_congested));
 284 }
 285
 286 enum {
 287         BLK_RW_ASYNC    = 0,
 288         BLK_RW_SYNC     = 1,
 289 };
 290
 291 void clear_bdi_congested(struct backing_dev_info *bdi, int sync);
 292 void set_bdi_congested(struct backing_dev_info *bdi, int sync);
 293 long congestion_wait(int sync, long timeout);
 294 long wait_iff_congested(struct zone *zone, int sync, long timeout);
 295
 296 static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi)
 297 {
 298         return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK);
 299 }
 300
 301 static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi)
 302 {
 303         return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY);
 304 }
 305
 306 static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi)
 307 {
 308         /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */
 309         return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB |
 310                                       BDI_CAP_NO_WRITEBACK));
 311 }
 312
 313 static inline bool bdi_cap_swap_backed(struct backing_dev_info *bdi)
 314 {
 315         return bdi->capabilities & BDI_CAP_SWAP_BACKED;
 316 }
 317
 318 static inline bool bdi_cap_flush_forker(struct backing_dev_info *bdi)
 319 {
 320         return bdi == &default_backing_dev_info;
 321 }
 322
 323 static inline bool mapping_cap_writeback_dirty(struct address_space *mapping)
 324 {
 325         return bdi_cap_writeback_dirty(mapping->backing_dev_info);
 326 }
 327
 328 static inline bool mapping_cap_account_dirty(struct address_space *mapping)
 329 {
 330         return bdi_cap_account_dirty(mapping->backing_dev_info);
 331 }
 332
 333 static inline bool mapping_cap_swap_backed(struct address_space *mapping)
 334 {
 335         return bdi_cap_swap_backed(mapping->backing_dev_info);
 336 }
 337
 338 static inline int bdi_sched_wait(void *word)
 339 {
 340         schedule();
 341         return 0;
 342 }
 343
 344 #endif          /* _LINUX_BACKING_DEV_H */